Speaking to BBC News, Major General James Everard, Assistant Chief of the General Staff, said:
We owe a huge apology to the families involved and those who will now be feeling stressful even if it doesn't affect them.
These were just tissue samples that we had failed to recover post-inquest and deal with in line with the families' wishes.
It's a failure of process, nothing more than that, but we absolutely recognise this will cause distress and we're deeply sorry."
More top news
Police divers have dragged the body of a man from the river Avon in Bristol city centre. A man was seen struggling in the water last night.
The new man in charge will watch his side from the Director's Box at Charlton this afternoon.
Police are resuming their search for a man who was last seen swimming in the river in the Welsh Back area. Divers have been deployed.